PersistentFieldStrategy (Tapestry API - 5.7.2)乐学网一站式学习平台

All Known Subinterfaces:

ClientPersistentFieldStorage

All Known Implementing Classes:

AbstractSessionPersistentFieldStrategy, ClientPersistentFieldStorageImpl, ClientPersistentFieldStrategy, EntityPersistentFieldStrategy, EntityPersistentFieldStrategy, FlashPersistentFieldStrategy, SessionPersistentFieldStrategy
```
public interface PersistentFieldStrategy
```
Defines how changes to fields (within components, within pages) may have their values persisted between requests. Different implementations store the field values in the session, on the client, or elsewhere.

Method Summary

All Methods Instance Methods Abstract Methods
Modifier and Type	Method	Description
`void`	`discardChanges(String pageName)`	Discards any saved changes for the name page.
`Collection<PersistentFieldChange>`	`gatherFieldChanges(String pageName)`	Finds all persistent changes previously stored for the named page (for the current active session or client).
`void`	`postChange(String pageName, String componentId, String fieldName, Object newValue)`	Posts a change of a persistent property.

- Method Detail
  - postChange
```
void postChange(String pageName,
                String componentId,
                String fieldName,
                Object newValue)
```
    Posts a change of a persistent property.
    
    Parameters:
    
    pageName - the name of the page containing the component
    
    componentId - the nested id path of the component (or null for the page's root component)
    
    fieldName - the name of the field whose persistent value has changed
    
    newValue - the new value for the field, possibly null
  - gatherFieldChanges
```
Collection<PersistentFieldChange> gatherFieldChanges(String pageName)
```
    Finds all persistent changes previously stored for the named page (for the current active session or client).
  - discardChanges
```
void discardChanges(String pageName)
```
    Discards any saved changes for the name page. There is no expectation that data already gathered from the strategy and presumably dumped into component instance fields will be affected, but future field access (within this request or a later one) will show no data for the indicated page.
    
    Parameters:
    
    pageName - logical name of page whose field persistent data should be discarded